This invention relates broadly to evaporative cooler devices. More specifically, the present invention relates to portable evaporative air coolers adapted for temporary use in vehicles.
Evaporative coolers can provide relatively inexpensive air conditioning in warm, dry environments with low relative humidity. They are most efficient when a significant wet bulb depression exists. In the past, evaporative air coolers have been widely employed in arid or even desert regions where they can provide twenty to thirty degrees of cooling relatively inexpensively. Evaporative air conditioners have previously been employed in vehicles and portable units are also known to the art. Since by their nature evaporative coolers must contain a significant volume of water, prior art coolers must be mounted within a level, relatively shock free location to prevent splashing and spilling.
Off-road vehicles such as bulldozers, agricultural implements and tractors usually lack air conditioning. Many boats, campers, and the like similarly lack effective cooling. In the summer months the cabs of typical earth moving machines can experience extremely uncomfortable temperatures, particularly in the American South and South-West.
Coolers that are fixedly mounted are too expensive; it simply costs too much for typical construction companies to provide each of the machines in their fleet with separate air conditioners. Many of the machines are used only during certain limited operations associated with a construction project. During a typical day, a workman may operate several machines, and switch between them as the job applications dictate. Interior space in such vehicles is typically very limited and the driver cabin is usually small and cramped, with room for little else than essentials. Known portable coolers intended for use in vehicles often have bulky cabinets that are difficult to position conveniently. The air circulating through the cooler creates turbulence in the water therewithin. When the vehicle encounters rough terrain, the water often splashes out of the canister, entering the air outlets.
If a cooler is to be employed in such vehicles successfully on a cost efficient basis, it should be easily moved between vehicles. Coolers that employ a mechanical pump are also extremely sensitive to changes in the water level such as is experienced in rough terrain applications. If too little water is available due to splashing or tilting, the pumps will not function properly and may be damaged. If too much water is introduced, it may enter the fans or air intakes and damage the system. Such problems with known prior art evaporative coolers make them disadvantageous for use in heavy construction equipment and off-road vehicles.
Evaporative air coolers are well known in the art. Typical evaporative air coolers employ a motorized fan to draw ambient air into the cooler housing. The air passes through a wet absorbent media for cooling. Various types of absorbent media have been employed, including trickle pads, fiber filters, and excelsior mats. When the water evaporates, heat is removed from the air, and the air is thus cooled. As the air temperature decreases, its relative humidity increases. The evaporative system will not function unless the water supply to the system is maintained.
U.S. Pat. No. 2,786,406 issued Mar. 26, 1957 discloses an evaporative cooler designed for window mounting. A rotating wick within the chamber humidifies air passing by and around it. Such systems are inefficient, and generally splash and spray water into the vehicle interior. Moreover, such coolers are not well suited for use with large equipment, where the operator is provided extremely little headroom or window access.
U.S. Pat. No. 4,798,060 issued Jan. 17, 1981 discloses a portable evaporative air cooler resembling an ice chest. An evaporative pad disposed within the cooler is rotated by an electric motor. As the pad is rotated, resultant vacuum draws ambient air into the cooler. Air is delivered from outside the vehicle via a flexible hose or duct which projects into the casing. Water is periodically injected into the wick pad by a pump-driven sprayer. In use, the cooler is filled with water and coupled to the vehicle battery by an electric cigar lighter connector. The air is cooled as it is drawn through the evaporative pad.
An evaporative cooler disclosed in U.S. Pat. No. 4,970,876 issued Nov. 20, 1990 comprises a liquid storage sump associated with a motor driven fan that is positioned beneath the dash of a standard automobile. The system comprises a plurality of air passageways in fluid flow communication with humidifying wicks. In one embodiment, a pump is provided to moisten the wicks.
U.S. Pat. No. 4,953,831 issued Sep. 4, 1990 discloses a low-volume evaporative air cooler that is suitable for installation in a vehicle. Air flow is established through a reduced diameter inlet and circulated through an absorbent wick by a squirrel cage fan. Air is drawn from the interior of the vehicle, circulated through the wick, and expelled through an adjustable louver vent. However, the system is disadvantageous because it employs a pump, is subject to damage under harsh environmental conditions, easily spills the contained water, and has limited potential for diverse mountings.
Hickley U.S. Pat. No. 4,926,656 issued May 22, 1990 discloses a cooling system that combines indirect and direct heat exchange. Air is first introduced into the apparatus by a blower that passes the air through a cooling coil and subsequently through an evaporative media. The evaporative pad is supplied with water circulated by a pump associated with the water storage sump in the rear of the device. The device is not suited to application as a portable system such as would be useful for rough-terrain vehicles.
My previous U.S. Pat. No. 4,977,756 is directed to an evaporative air cooler for fixed applications. The latter system is not well-adapted to application in rough-terrain vehicles and heavy equipment. Other less relevant evaporative coolers designed for vehicles are disclosed in the following U.S. Pat. No. 3,978,174 issued Aug. 31, 1976, U.S. Pat. No. 3,552,097 issued Jan. 5, 1971, and U.S. Pat. No. 3,372,911 issued Mar. 12, 1968.
Hence, it is desirable to provide a convenient, lightweight portable evaporative air cooler that can be readily adapted for use in vehicles subjected to off-road conditions. Such a cooler must be compact, and should be well adapted for temporary mounting in a variety of vehicles in a variety of configurations.